1. Field of the Invention
This invention relates in general to plastic bag packs and, in particular, to a wicketless plastic bag pack and a method for making the pack. More specifically, but without restriction to the particular embodiment hereinafter described in accordance with the best mode of practice, this invention relates to a saddle pack of plastic bags that utilizes a minimum of disposable shipping materials and ultrasonic assembly of the wicketless plastic bag saddle pack.
2. Discussion of the Prior Art
The art of assembling bag packs employed in automated industrial bagging operations for packaging products like bread, or other consumer goods, typically involves bundling a stack of bags between two supporting boards with a disposable wicket secured by grommets.
The thermoplastic bags customarily used for packaging consumer products include a bottom edge which may be gussetted, top and bottom walls or front and back walls, depending on the orientation of the bag, a pair of side edges, and an open top end. The material forming the bottom or back wall has a lip portion extending beyond the open end of the bag. A perforated tear line may be formed between the open end of the bag and its lip portion. This tear line allows the bag to be removed from the lip portion as required during bagging operations. The lip portion is also provided with a pair of locating holes. As an alternative to the perforated tear line, top notches may be formed above the locating holes so that the bag may be torn through the notches during the bagging operation. In the assembly process of the bag pack, a U-shaped wicket is inserted through two corresponding locating holes in a first supporting board. As the thermoplastic bags issue off the production line, they are consecutively stacked upon the first support board with their respective locating holes placed over the extending prongs of the wicket. Once a desired number of thermoplastic bags is stacked upon the first board, a second supporting board with corresponding locating holes is placed over the wicket prongs to cover the top of the stack. Rubber grommets are moved down the wicket prongs to securely sandwich the stack of thermoplastic bags between the supporting boards. The bag pack is shipped in this condition to the industrial producer. Bagging equipment utilized by the industrial producer includes a wicket holder for positioning the stack of bags in relation to the production line. Pressurized air is employed to open the next consecutive bag on the pile so that product issuing off the production line is directed into the bag. The filled bag is then removed from the equipment wicket by tearing the bag from its lip portion along the perforated tear line or by tearing through the top notches above the locating holes. When the bagging equipment needs a resupply of bags, an equipment operator removes the rubber grommets and supporting boards from a new bag pack and places the new stack of bags on the wicket holder of the bagging equipment.
Use of this type of prior thermoplastic bag pack involves a waste of packing materials since the rubber grommets, supporting boards, and bag pack wickets are discarded when the stack of bags is mounted on the bagging equipment. In addition to this drawback, costly operator time is required in removing these materials from each bag stack. A further limitation relating to lost time is possible separation of the individual bags from the bag stack. Bagging machine down-time is caused by loose bags which can cause product to miss proper placement into a respective bag. This may result in an unwanted slow-down of the production line. Lastly, industrial producers encounter the cost of disposal in properly storing and hauling away the accumulation of these packing materials.
Another environment in which plastic bag packs are utilized is behind the deli counter or in the produce section of a grocery store. The plastic bags used in these situations are employed by the deli counter person to bag or wrap, for example, sliced meats, smoked fish, cheese, and other items commonly available from the deli. In the produce section, plastic bags are used by the consumer to individually bag, by item type, fruits and vegetables selected for purchase. Prior bag packs used behind the deli counter have included the prior art bag pack with disposable shipping materials discussed above. This type of bag pack and the well known roll of thermoplastic bags with twist-ties, have also been used in the produce section.
Recent developments in the thermoplastic bag pack art have lead to the advent of saddle packs of thermoplastic bags. The individual bags of the prior art saddle packs are formed from a continuous blown film tube of thermoplastic material. In some cases, the tube is extruded with zipper material. Once the tube is cooled, it is run through nip rollers to create a lay-flat tube for producing saddle bags. The cooled tube is cut into lateral sections to form a two-sheet saddle bag blank. The bottom edges of the bags are thereby formed by the folded edges of the flat tube. On one side of a two-sheet common lip area, the first sheet is slit from the tube segment and removed. The second sheet of the common lip area is perforated to provide a tear line between the open end of each bag and edge of the lip segment. This process forms a saddle bag configuration with a one-sheet common lip portion between the bags. The side edges are sealed together while the common lip is provided with a pair of locating holes. These individual saddle bags are then stacked in a pack. The saddle bag pack is typically suspended over a mounting bar with the pad of lips secured thereon by a wicket or stacking pins. Each of the two hanging bag packs of the saddle pack are thus simultaneously reachable by two customers in the produce section or two counter people behind the deli. While these saddle packs have proved valuable, particularly during peak hours when many consumers are shopping or counter people are rushing back and forth in an effort to quickly serve waiting customers, they are considerably more costly than conventional bag packs or rolls. In addition, the machinery required to produce the opposing bags from a blown tube of plastic material is expensive and not easily retooled to manufacture other products.